Chmod Calculator
Free online chmod calculator to visualize and calculate Linux file permissions with checkboxes. Instantly convert between numeric (755, 644) and symbolic notation (rwxr-xr-x). Supports special permissions like setuid, setgid, sticky bit.
What is chmod?
chmod (change mode) is a Linux/Unix command that changes the access permissions of files and directories. It determines who can read, write, or execute a file.
What does chmod 755 mean?
chmod 755 means the owner has read, write, and execute permissions (7=rwx), while group and others have read and execute permissions (5=r-x). Commonly used for executable scripts and directories.
How to manually calculate chmod values?
Each permission has a numeric value: read=4, write=2, execute=1. Add these values for each category (owner, group, others). For example, owner with rwx = 4+2+1 = 7.
What do rwx permissions mean?
rwx stands for read (r), write (w), and execute (x). Read allows viewing file content, write allows modifying it, and execute allows running it as a program or script.
What are special permissions like setuid, setgid, and sticky bit?
setuid (4000) makes a file run with the owner's privileges, setgid (2000) makes it run with the group's privileges, and sticky bit (1000) restricts deletion of files in a directory to the owner only.
What permissions should web server files have?
Web files typically use 644 (rw-r--r--) for HTML/CSS/JS files and 755 (rwxr-xr-x) for directories and CGI scripts. Never use 777 as it allows anyone to modify files.
How to use symbolic notation with chmod?
Symbolic notation uses letters like u (user), g (group), o (others), a (all) and operators + (add), - (remove), = (set). For example, chmod u+x file adds execute permission for the owner.
Is this tool private?
Yes, this chmod calculator runs 100% in your browser. No data is sent to any server, ensuring complete privacy and security.
How to Use Chmod Calculator
Work out Linux file permissions visually with checkboxes, and convert between numeric modes like 755 or 644 and symbolic notation like rwxr-xr-x. Includes setuid, setgid and the sticky bit. Runs entirely in your browser.
- Tick the checkboxes for owner, group and others to grant read, write or execute rights.
- Enable setuid, setgid or the sticky bit for special cases such as shared directories.
- Type a numeric mode like 755 into the input that shows the '755' placeholder to load it into the checkboxes.
- Read the matching symbolic string (e.g. rwxr-xr-x) and the octal digits from the summary.
A common safe setup is 755 for directories and 644 for files — avoid 777 except for temporary testing.
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